Clarify search behavior for multi-instance fields

docs/5.x/system/searching.md

@@ -267,7 +267,7 @@ This is an extreme example—but it shows how quickly exact or near-exact matche
 
 ## Configuring Custom Fields for Search
 
-Each element type makes basic details, called _searchable attributes_, available as search keywords. It’s common to search for entries by title, for example, or for users matching a name or email address. (We just looked at these in the [Searching for Specific Element Attributes](#searching-for-specific-element-attributes) table.)
+Each element type makes basic details, called _searchable attributes_, available as search keywords. It’s common to search for entries by title, for example, or for users by their name or email address. (We just looked at these in the [Searching for Specific Element Attributes](#searching-for-specific-element-attributes) table.)
 
 You can configure any [custom field](fields.md) to make its content available for search by enabling **Use this field’s values as search keywords**:
 
@@ -281,6 +281,17 @@ For Matrix fields, the top-level **Use this field’s values as search keywords*
 For relational fields like [Assets](../reference/field-types/assets.md), [Categories](../reference/field-types/categories.md), and [Entries](../reference/field-types/entries.md), the setting determines whether titles of related elements should factor into search results.
 :::
 
+### Multi-Instance Fields
+
+When a field is marked as searchable, keywords for _all_ instances of that field on an element are combined into a single index, and their handles are treated as aliases. For example, a  [plain text](../reference/field-types/plain-text.md) field added to a field layout multiple times (with, say, handles `summary` and `byline`), Craft does not distinguish which field instance the keywords came from—this means that [searching against specific element attributes](#searching-for-specific-element-attributes) may produce unexpected results:
+
+- Searching for `summary:daisy` may return entries that included the name _Daisy_ in the `byline`;
+- Searching for `byline:rose` may return entries that mention the flower _rose_ in their `summary`;
+
+::: tip
+If your application relies on distinct keywords, create individual fields.
+:::
+
 ## Indexing Criteria
 
 Any time an indexable attribute or field on an element is updated (as indicated by Craft’s change-tracking feature, which powers drafts and revisions), an “Updating search indexes” job is pushed into the queue. Prior versions generate an indexing job whenever an element with _any_ searchable attributes or fields is saved, regardless of whether or not those specific attributes changed.
@@ -289,7 +300,7 @@ The [eligible properties](#searching-for-specific-element-attributes) differ for
 
 ## Searching Nested Elements
 
-In Craft 5, [entry queries](../reference/element-types/entries.md#querying-entries) return nested elements, by default. To search only for entries that belong to a section (those that are not owned by another entry), apply the `.section()` param:
+In Craft 5, [entry queries](../reference/element-types/entries.md#querying-entries) return nested elements, by default. To search only for entries that belong to a section (those that are not owned by another entry), use the `.section()` param:
 
 ```twig
 {% set results = craft.entries()
@@ -299,7 +310,7 @@ In Craft 5, [entry queries](../reference/element-types/entries.md#querying-entri
   .all() %}
 ```
 
-If you want entries in any section, and would prefer to not maintain a list of specific sections (or _excluded_ sections, with `.section(['not', 'home', 'suppliers'])`) in your template, pass an asterisk <Since ver="5.2.0" feature="Querying for non-nested entries with the special “section wildcard”" /> (`*`):
+If you want entries in _any_ section, and would prefer to not maintain a list of specific sections (or _excluded_ sections, with `.section(['not', 'home', 'suppliers'])`) in your template, pass an asterisk <Since ver="5.2.0" feature="Querying for non-nested entries with the special “section wildcard”" /> (`*`):
 
 ```twig{2}
 {% set results = craft.entries()

docs/5.x/upgrade.md

@@ -98,7 +98,7 @@ Read more about this part of the upgrade in the [Database Character Set and Coll
 
 ## Cleanup + Optional Steps
 
-### Field and Entry Type Consolidation
+### Field and Entry Type Consolidation <Since ver="5.3.0" feature="Field type and entry type consolidation commands" />
 
 Craft 5.3 introduced three new commands for consolidating fields and entry types, post-upgrade:
 
@@ -127,9 +127,11 @@ Craft will audit your fields, and propose batches of merge candidates. To accept
 The usage of any merged fields in field layouts and templates will remain the same after merging global field definitions. Any overridden names, handles, instructions, and so on will remain. One exception here is if a name or handle override is present but the same as the merged global field’s name: Craft clears the override so that it can be better kept in sync, moving forward.
 
 ::: tip
-Don’t like how Craft grouped some of the fields? You can skip any proposed merge and come back to the command later—say, after [manually merging](#manually-merging-fields) a few of the fields. 
+Don’t like how Craft grouped some of the fields? You can skip any proposed merge and come back to the command later—say, after [manually merging](#manually-merging-fields) a few of the fields.
 :::
 
+Merged fields’ search keywords are also combined, which may affect the quality of results when [searching by field handles](system/searching.md#multi-instance-fields).
+
 #### Manually Merging Fields
 
 For any additional fields you wish to merge (or merge candidates you skipped in the previous step), run the `fields/merge` command as many times as necessary to consolidate them: